1. Field of the Invention
The present invention relates to a radiography device having an X-ray source and an X-ray receiver.
2. Description of the Prior Art
Radiography devices are usually constructed such that the X-ray source and the X-ray receiver are fixedly arranged at a common mechanically rigid carrier, for instance a C-arm. The X-ray source and the X-ray receiver are arranged relative to one another at this carrier so that the center ray of an X-ray beam emanating from the X-ray source strikes on the detector surface of the X-ray receiver approximately in the middle thereof. The carrier typically can be moved relative to a subject that is being examined, the X-ray source and the X-ray receiver being constantly aligned relative to one another regardless of the displacements of the carrier.
A disadvantage of such rigid carriers is that they limit or obstruct the access to the patient in medical examinations.
German OS 196 11 705 teaches a radiography device with an X-ray source and an X-ray receiver, wherein the X-ray source and the X-ray receiver are respectively mounted at a stand such that they can be displaced three-dimensionally in space. In order to align the X-ray source and the X-ray receiver relative to one another such that the center ray of an X-ray beam emanating from the X-ray source strikes the detector surface of the X-ray receiver approximately in the middle thereof, detectors are provided in space that detect the positions of the X-ray receiver in space. Using the detected positions of the X-ray receiver, it is possible to adjust the X-ray source relative to the X-ray receiver such that the center ray of the X-ray beam emanating from the X-ray source strikes the detector surface of the X-ray receiver approximately in the middle thereof. The X-ray source thus always tracks the X-ray receiver.
The technical outlay required for the detection of the position of the X-ray receiver and for the tracking action of the X-ray source, which includes detectors that are arranged in space and a control means for the X-ray source and a control computer for the X-ray receiver, prove disadvantageous.
It is an object of the present invention to provide a radiography device wherein the X-ray source and the X-ray receiver are arranged such that they can be moved relative to one another freely, while always being aligned relative to one another, in a technically simple manner.
This object is inventively achieved in a radiography device having an X-ray source and an X-ray receiver which are each arranged so as to be moved freely in space at a robot arm of a robot having a number of arms that can be displaced relative to one another by motors, and having a central control unit which controls the displacement of the robot arms of the two robots such that the X-ray source is always oriented to the X-ray receiver for purposes of acquiring images. The X-ray source and the X-ray receiver are thus arranged at separate robot arms, respectively, so as to be freely displaceable in space. Because a mechanically rigid carrier that accepts both the X-ray source and the X-ray receiver is not used, in the case of medical radiological exams there results an improved access to a patient to be examined with the radiography device. Robots having a number of arms that can be displaced in a motor-driven manner relative to one another about axes, at which arms the X-ray source and the X-ray receiver respectively are arranged, offer a variety of adjustment possibilities for individual X-ray projections as well as multiple possibilities for movement sequences for capturing a series of radiographic images wherein the X-ray source and the X-ray receiver are displaced relative to an examination subject. The displacement of the robot arms of the two robots is controlled by the central control unit of the radiography device, so that the X-ray source and the X-ray receiver are always oriented to one another such that the center ray of an X-ray beam emanating from the X-ray source strikes the detector surface of the X-ray receiver approximately in the middle thereof in both individual X-ray projections (exposures) and in a series of X-ray projections (exposures).
In a version of the invention the robot arm at which the X-ray source is arranged and/or the robot arm at which the X-ray receiver is arranged have at least three degrees of freedom with respect to displacement of that robot arm. In this way, many adjustment possibilities of the X-ray source and the X-ray receiver are available merely by displacing the robot arm.